Catheters have been in use for many years and traditionally comprise a flexible and resilient body portion having, generally, an inflation lumen and one or more other lumens for withdrawing blood specimens, monitoring blood pressure and temperature, or introduction of drugs extending through the body portion. An opening is provided in the catheter wall extending into and communicating with the inflation lumen and an inflatable balloon is secured to the catheter over the opening thereby permitting the inflation of the balloon by introducing a fluid pressure through the inflation lumen. The distal end of the catheter adapted for insertion into the patient is normally rounded. Openings are provided in the catheter wall communicating with the lumens used for withdrawing blood specimens, monitoring blood pressure and temperature, or introduction of drugs, the openings generally being located intermediate the balloon and the catheter distal end.
At the opposite, proximal, end of the catheter, funnell portions are provided communicating with the lumens. In multilumen catheters the tubular body is normally bifurcated adjacent to the proximal ends of the inflation lumen.
U.S. Pat. No. 4,003,382 which discloses a method for preparing thermosetting polyurethane balloons that are added to a catheter body made of thermoplastic polyurethane. The balloon is produced by first applying a heat activatable polyurethane adhesive to a mandrel either in strips or from solution. A thermosetting polyurethane balloon is then formed on the mandrel using a mold which is filled with the thermosetting polyurethane and heated to form and cure the polymer. The resulting product is a polyurethane tubular sleeve having polyurethane adhesive bands on the inside of the tube at each end. This balloon is then slipped over a catheter covering the inflating lumen, and sealed in place by heat activating the polyurethane adhesive bands. This construction results in a catheter in which the distal end is a sharp protrusion extending beyond the balloon thereby presenting a hazard to a patient in whom the catheter has been inserted.
U.S. Pat. No. 3,746,003 and a related U.S. Pat. No. 3,634,924 disclose a balloon construction which to some extent alleviates the problem of a hazardous lead point on the catheter by utilizing a balloon construction wherein the tube from the the balloon is attached to the distal end of the catheter and everted. The result is a balloon configuration which when inflated, extends forward of the area of attachment and the distal end of the catheter. In the '003 and '924 patents, however, the balloon is held in place by winding of thread over a metal ferrules. The function of the ferrules is to prevent the windings from collapsing the catheter tube. Inadvertent dislodgement of windings result in a hazard to the patient.
U.S. Pat. No. 4,403,084 discloses a crystalline grindable polyurethane prepolymer. The polymer can be formed into objects by causing the prepolymer to form a film on a mandrel heated above the melting point of the prepolymer. The film is then heated to cure it. The use of the prepolymer to prepare surgical gloves in this manner is disclosed.